The PRESERFLO MicroShunt has become an increasingly familiar option for lowering intraocular pressure (IOP) in progressive glaucoma, offering a less invasive alternative to trabeculectomy with a favorable biocompatibility profile. But a new Graefe's Archive for Clinical and Experimental Ophthalmology report has highlighted an underappreciated risk (already noted in the MicroShunt manufacturer's guidelines): exposure of the device to petrolatum-based ophthalmic ointment may cause marked swelling and structural failure.
The study authors describe three clinical cases in which MicroShunt swelling was observed after ointment use, alongside an in vitro experiment designed to confirm causality and explore the mechanism. In all three clinical cases, the MicroShunt became exposed or was at risk of exposure (for example, after bleb leak or conjunctival rupture), and a petrolatum-based ointment was used as part of postoperative management. Within days to weeks, the explanted devices were visibly enlarged, friable, and in two cases fractured during removal, including loss of a fin. Optical coherence tomography (OCT) imaging suggested swelling was localized to the exposed, subconjunctival portion near the fins, while the intraocular distal segment remained relatively unchanged; importantly, luminal patency appeared preserved in at least one case.
To strengthen the association, the authors examined four explanted MicroShunts from patients without ophthalmic ointment exposure. None showed swelling, including one case with MicroShunt exposure managed without ointment. This comparison supports the idea that exposure alone is not sufficient — direct contact with petrolatum-based ointment appears to be the key trigger.
For clinicians, the message is practical and urgent: avoid petrolatum-based ophthalmic ointments when the MicroShunt is exposed — and consider avoiding them when conjunctival integrity is compromised or a bleb leak is present. This is a rare but preventable complication, and one that could have serious implications for device integrity and surgical outcomes.
The study authors describe three clinical cases in which MicroShunt swelling was observed after ointment use, alongside an in vitro experiment designed to confirm causality and explore the mechanism. In all three clinical cases, the MicroShunt became exposed or was at risk of exposure (for example, after bleb leak or conjunctival rupture), and a petrolatum-based ointment was used as part of postoperative management. Within days to weeks, the explanted devices were visibly enlarged, friable, and in two cases fractured during removal, including loss of a fin. Optical coherence tomography (OCT) imaging suggested swelling was localized to the exposed, subconjunctival portion near the fins, while the intraocular distal segment remained relatively unchanged; importantly, luminal patency appeared preserved in at least one case.
To strengthen the association, the authors examined four explanted MicroShunts from patients without ophthalmic ointment exposure. None showed swelling, including one case with MicroShunt exposure managed without ointment. This comparison supports the idea that exposure alone is not sufficient — direct contact with petrolatum-based ointment appears to be the key trigger.
For clinicians, the message is practical and urgent: avoid petrolatum-based ophthalmic ointments when the MicroShunt is exposed — and consider avoiding them when conjunctival integrity is compromised or a bleb leak is present. This is a rare but preventable complication, and one that could have serious implications for device integrity and surgical outcomes.
